In their study, the lenses delivered the glaucoma drug latanoprost (brand name Xalatan) continuously to animals for a month. It's hoped that some day such lenses will replace eye drops now used to treat the eye disease, the researchers said.

"In general, eye drops are an inefficient method of drug delivery that has notoriously poor patient adherence," study lead author Dr. Joseph Ciolino, a cornea specialist at the Massachusetts Eye and Ear Infirmary, said in an infirmary news release. "This contact lens design can potentially be used as a treatment for glaucoma and as a platform for other [eye] drug delivery applications."

Glaucoma is the leading cause of irreversible blindness worldwide.

The lenses, which appeared safe in cell culture and animal studies, are the first to be shown to release drugs for this long in animals, according to the researchers. The study appears online and in the January print issue of the journal Biomaterials.

The lens the research team developed "is capable of delivering large amounts of drug at substantially constant rates over weeks to months," Daniel Kohane, director of the Laboratory for Biomaterials and Drug Delivery at Boston Children's Hospital, said in the news release.

Ciolino said a noninvasive method of sustained eye-drug delivery could save millions of people from blindness if it helps them comply with their medication regimen.